title: The silent phase of diffuse low-grade gliomas. Is it when we missed the action?
abstract: BACKGROUND
  It is commonly believed that, before being diagnosed after onset of symptoms, diffuse low-grade glioma evolve silently for a long time. The present study aimed to estimate for the first time the exact duration of this silent phase, during which the glioma is radiologically visible but undiscovered.
  
  
  METHODS
  We retrospectively reviewed our French national database of diffuse low-grade glioma, searching for patients with an MRI-based assessment of their velocity of diameter growth at diagnosis and before any treatment (at least three MRIs over more than 6 months). For each patient, the duration of the silent phase was estimated by the formula: duration = initial diameter / initial velocity of growth.
  
  
  RESULTS
  A total of 148 patients were included in the study. The mean lead-time duration (i.e., duration of the silent phase) was 14.0 ± 7.8 years (median, 11.6 ; range, 1.6-39.4). The lead-time is statistically not correlated to the tumor volume. It is markedly decreasing with the velocity of diameter expansion.
  
  
  CONCLUSIONS
  Diffuse low-grade glioma are radiologically detectable but clinically silent for more than a decade. Such a long period of silent evolution could explain our current failure to cure these tumors. It can also be viewed as a window of opportunity to detect these tumors earlier, suggesting the need to set up a screening program.
authors.affiliation: Department of Neurosurgery, Saint-Anne Hospital, Paris, France.
authors.forename: Johan
authors.initials: J
authors.lastname: Pallud
authors.forename: Laurent
authors.initials: L
authors.lastname: Capelle
authors.forename: Luc
authors.initials: L
authors.lastname: Taillandier
authors.forename: Mathilde
authors.initials: M
authors.lastname: Badoual
authors.forename: Hugues
authors.initials: H
authors.lastname: Duffau
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mandonnet
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy*; D005260:Female; D005910:Glioma / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D012189:Retrospective Studies; D016896:Treatment Outcome; D047368:Tumor Burden / Q000502:physiology